﻿using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApp1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {
            double a = System.Convert.ToDouble(this.textBox1.Text) + System.Convert.ToDouble(this.textBox2.Text);
            this.textBox3.Text = a.ToString();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            double a = System.Convert.ToDouble(this.textBox1.Text) - System.Convert.ToDouble(this.textBox2.Text);
            this.textBox3.Text = a.ToString();
        }

        private void button3_Click(object sender, EventArgs e)
        {
            double a = System.Convert.ToDouble(this.textBox1.Text) * System.Convert.ToDouble(this.textBox2.Text);
            this.textBox3.Text = a.ToString();
        }

        private void button4_Click(object sender, EventArgs e)
        {
            double a;
            if (this.textBox2.Text != "0")
            {
                a = System.Convert.ToDouble(this.textBox1.Text) / System.Convert.ToDouble(this.textBox2.Text);
                this.textBox3.Text = a.ToString();
            }
            else
            {
                this.textBox3.Text = "ERROR";
            }
        }
    }
}